Seismic energy absorption systems, namely, seismic resistant systems, seismic resisting systems, and seismic isolation systems have recently come into widespread use, and seismic isolation rubber systems comprising alternately laminated rubber composition and rigid plates are used for bridge bearings and building base isolation. The seismic isolation rubber system is a system wherein the alternately laminated rubber composition and rigid plates exhibit reduced shear rigidity by being very hard in the vertical direction and flexible in the horizontal direction. Such seismic isolation rubber system functions to displace the vibration cycle intrinsic to the building from the seismic cycle to thereby remarkably reduce the acceleration applied to the building in the earthquake. The rubber composition used for such purpose is required to have high damping capacity so that the vibration is converted into heat to thereby damp the seismic energy.
In conventional rubber compositions, such high damping capacity has been realized by increasing the amount of carbon black blended or by blending a resin component. However, it has been difficult to simultaneously realize the high damping capacity and other physical properties required, and such attempt has been associated with the problem of hardening.
The present invention has been completed in view of the situation as described above, and an object of the present invention is to provide a rubber composition which offers the high damping capacity wherever it is used.